[Amps] Transformer Calcs

[Bill, W6WRT]

ORIGINAL MESSAGE:

On Fri, 11 Jun 2010 11:08:10 -0700, Patrick Barthelow
<apolloeme at live.com> wrote:

>For a KW level  HV transformer, is there much difference between the temp that you can touch and measure, say at the outside laminations, and perhaps the more important temperatures in the core center, and the copper wire, bobbins, windings, and paper/plastic insulation materials that we cannot see, inside?
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>And, a related question, from a cold room temperature start, if you could measure the surface temperature of the laminations of a, say, Heathkit SB 220 amp that was being used with a lot of transmit time, on CW at 1KW out,  How long would it be before the outside lamination temperature could give a representative temperature of the more critical inside core temperatures?    Could  there be, say, 50 degree F temperature difference between inside and outside when the Amp is producing 1KW RF output?  If you can cool the outside of the transformer with continuous airflow from a  muffin fan, or better, would that reduce significantly the inside core temperature?

REPLY:

Those are all good questions. Wish I knew the answers. The only thing
for sure is if the outside seems excessively hot, the inside is more
so. 

73, Bill W6WRT